Champlain Towers South Investigation Nears Completion of Technical Work

Recent interviews and analyses of test results and physical evidence by the National Institute of Standards and Technology (NIST) reinforce preliminary findings that the 2021 failure of the Champlain Towers South building likely started in its pool deck rather than in the tower itself. The investigation has also identified indications of the building's distress that were visible in the weeks before the partial collapse of the building in Surfside, Florida.

Investigative lead Judith Mitrani-Reiser and co-lead Glenn Bell presented an update on the NIST investigation today at a virtual meeting of the National Construction Safety Team (NCST) Advisory Committee. Their presentation summarized the investigation's activities and preliminary findings provided in previous updates, including an extensive video released in June 2025, and highlighted significant progress in the failure analysis since the June update.

Bell described the team's current efforts to advance its evaluations of potential failure initiation scenarios through computer simulations, supported by the results of large-scale structural testing and evidence of the building's distress in the weeks before failure. The team has also been refining its analysis of the impacts of steel reinforcement corrosion, concrete shrinkage, and improperly built construction joints in the pool deck slab.

According to Bell, the results of these efforts "indicate that it is more likely that the failure started in a pool deck slab-column connection."

Bell also explained how the results of large-scale structural testing and computer analyses of video footage captured at the time of the collapse shed light on how the collapse progressed from the pool deck into and through the tower.

Mitrani-Reiser highlighted indications that the building was in distress in the weeks before the collapse. These included a sliding glass door that came off its frame, the previously reported horizontal crack in a planter wall and distress where the wall meets a planter box, and the vertical shifting of a gate, causing it to jam so that it could not be opened. All of these issues were concentrated in a small area of the pool deck and street-level parking deck, which has been confirmed to have begun collapsing at least seven minutes before the tower.

Additionally, the day before the collapse, water was seen leaking from the ceiling of the garage in an area that had been the site of many cracks and repairs over the years. The flow of water dramatically increased in the hours before the collapse.

The team is now focused on completing its technical work by the end of 2025 and drafting its reports, which will include a summary report and six subject-focused technical reports.

The team is engaging with key stakeholder groups in the building design, construction, inspection, evaluation and maintenance fields to disseminate preliminary analysis results and gather information that will inform technical and policy recommendations. This effort will help to ensure that the investigation's findings and recommendations bring improvements to building safety, both for the construction of new buildings and for the ongoing integrity of existing buildings.

"This tragic event has revealed flaws in our systems, and quality is at the heart of it," said Mitrani-Reiser.

The Champlain Towers South investigation team plans to provide its next detailed public update in Spring 2026.